U.S. officials who have been toughening their stance toward Iran in recent weeks have said almost nothing about its presidential election, now less than one month away.

And, some Iran observers say the silence regarding the May 19 vote could be a reflection of broad skepticism about its significance.

Wednesday during a State Department briefing, U.S. Secretary of State Rex Tillerson made no mention of the Iranian presidential election as he gave his most detailed outline yet of the Trump administration’s toughening Iran policy. But he did accuse Tehran of being the world’s “leading state sponsor of terrorism” and carrying out “provocative actions” that threaten the United States, such as ballistic missile testing.

Republican U.S. Senator Bob Corker revealed a delay in advancing a Senate bill imposing new sanctions on Iran as he spoke during a Senate hearing on the European Union as a U.S. "partner against Russian aggression," April 4, 2017.

On Capitol Hill

On Capitol Hill, U.S. lawmakers also have said little about the impending Iranian vote. There has been no action in the Senate or House since legislation was introduced by bipartisan groups of lawmakers on March 23. The legislation would impose new U.S. sanctions on Iran in retaliation for its January ballistic missile test.

A sponsor of the Senate bill, Republican Bob Corker, said at a hearing this month that the Iran sanctions legislation has been delayed by concerns about “elections that are coming up,” an apparent reference to the May 19 vote.

It may be too soon to expect the 3-month-old Trump administration to express any view on Iran’s electoral process, said Alex Vatanka, an Iran observer at the Washington-based Middle East Institute.

“The administration really has not had the time to get down to the key aspects of Iranian domestic politics, and whether the U.S. needs to or can in any way take sides in support of one Iranian faction against another,” Vatanka told VOA Persian in an interview.

FILE- Iranian cleric Ebrahim Raisi registers his candidacy for the May 19 presidential elections at the Interior Ministry in Tehran, Iran, April 14, 2017. More than 1,600 people registered to run.

In a Thursday report, Iranian state television said the country’s 12-member Guardian Council has vetted and approved six candidates to compete in the May 19 presidential vote, most notably the relatively moderate incumbent President Hassan Rouhani, and prominent conservative Ebrahim Raisi, appointed last year as custodian of one of Iran’s holiest shrines by Iranian Supreme Leader Ayatollah Ali Khamenei.

Behnam Ben Taleblu, a Washington-based Iran analyst at the Foundation for Defense of Democracies, says Iran’s system of vetting candidates for a presidential post that is subordinate to Iran’s supreme leader has long been understood by U.S. executive and legislative branches of government.

“They know Iran’s president is not the ultimate commander in chief nor the ultimate person who has the say over foreign policy, that person is the supreme leader and his affiliated institutions like the Islamic Revolutionary Guard Corps,” Taleblu said.

Presidential influence

But Washington still has a basis for being interested in who wins the presidential race, Taleblu said.

“Iranian presidents can say or do things to impact the tone of Iran’s foreign policy,” he added.

Vatanka said that tone would be evident if Rouhani wins re-election.

“In that case,” he said, “there is a strong likelihood that Rouhani can continue to push for Iran to enter mainstream international politics.”

A win by a conservative candidate such as Raisi could push Iran in a different direction, Vatanka said.

“Hard-line challengers to Rouhani openly have said that the 2015 nuclear agreement (between Rouhani’s government and six world powers) has not delivered what Rouhani promised (in economic benefits), and have suggested it might not be a bad idea to revisit this deal or to even walk away from it,” he said.

Taleblu says there is an even greater reason for the U.S. to care about Raisi’s presidential candidacy.

“Should he win, Raisi has a clear path to being the likely candidate for Iran’s next supreme leader,” he said. “But should Raisi lose, that would erode the little political clout that he has, in terms of public support, and likely negatively impact his chances to become the supreme leader.”

Vatanka says Raisi, a former little-known Iranian judiciary official, is unlikely to win the presidency without election-rigging help from his conservative allies. The last Iranian presidential vote to be overshadowed by allegations of massive fraud — conservative Mahmoud Ahmadinejad’s 2009 re-election — triggered months of nationwide streets protests.

“The Obama administration, which at the time was very new, didn’t know what to do about the unrest that engulfed Iran in 2009,” Vatanka said. “The Trump administration can start thinking about what would be their response to more political turmoil — would they seek to engage directly with Iran’s so-called moderates, or would they think it is not worth the time? That is the big test.”